Tim Cook, Appls’s top executive, during a developer conference on Monday , unveiled new tools to monitor smartphone usage and will start offering new software for hardcore users of iPhones and tablets who want to limit their hours online.The initiative, called “Digital Health,’’ is designed to wean heavy users away from their devices.Cook said earlier this year he did not want his young nephew to be on a social network.He also suggested people should limit their time on mobile phones.“I don’t believe in overuse,” he said. “I’m not a person that says we’ve achieved success if you’re using it all the time. I don’t subscribe to that at all.”

Apple users can set limits on the phone in general, or choose to set limits for certain apps, such as social media. When the limit is reached, the device will shut down. Those who choose to use this new feature can also sync the monitor limits among devices, so you can’t switch over and keep surfing on your iPad or Macbook.